1. Field of the Invention
The invention relates to water-soluble platinum complexes of cis-diaminocyclohexanol or cis-diaminocyclohexane, and to anti-tumor agents containing the same.
2. Description of the Background
Since the high anti-tumor activity of cisplatin [cis-dichlorodiamineplatinum(II)] was reported in Nature, 222, 385 (1969), extensive studies have been made on this compound as an anti-tumor agent. As a result, it is widely used clinically as an anti-cancer agent of high efficacy throughout the world. However, it has severe side effects, such as toxicity to the kidney, nausea, emesis and bradyacusia, and readily causes drug resistance. Under the circumstances, researchers over the world have attempted to synthesize second-generation platinum complexes which have medical efficacy comparable with cisplatin or but which are free from toxicity to the kidney and other side effects, and show no cross resistance with cisplatin. As a result, the platinum(II) complex of cis-dichloro-1,2-diaminocyclohexane has been found to have some promise [Chem. Biol. Interactions, 5, 415 (1972)], but this substance has low solubility in water. Additionally, platinum complexes have been prepared by using diaminocyclohexanols as the amine component, which complexes show high inhibitory action particularly against the growth of L 1210 (mouse leukemia cells) and S-180. See Japanese Patent Kokai No. 286396 (1986).
However, all of these complexes have poor water solubility, which make them impractical for clinical use.
Thus, a need continues to exist for a platinum-containing anti-tumor agent which is readily soluble in water, exhibits high anti-tumor activity, has low toxicity and exhibits no cross-resistance with cis-platin.